Can catch pubic lice definately from public toilets?

Not likely: Pubic lice are very slow moving, and do not live very long at temperatures lower than the human body. Transmission is usually through prolonged intimate contact, although anything is possible. Symptoms of itching or sores in the pubic region should be evaluated.

VERY unlikely: “There are documented cases of transmission from toilet seats, beds, and egg-infested loose hairs dropped by infested persons on shared objects. REF: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4594412/ . It would be highly unlikely to get lice from a toilet seat because they will die fairly quickly if away from a warm body. They don’t have the capacity to move on smooth surfaces.